Flocking refers to the collective and coherent motion of a large group of animals. In this paper, a procedural animation generation technology of virtual fish flock is described. In our work, each animated character, symbolized by fish, is implemented as an independent actor that navigates according to its local perception of the environment. Motion of the actor obeys the laws of simulated physics, and a set of behaviors are programmed into it by the animator. Flocking behaviors of separation, alignment and cohesion are be recreated. As such, there is no need to script the motions of each individual fish. These kinds of systems are commonly employed when constructing a large-scale battle or a herd of animals. With this work, we are able to simulate flocking behavior using autonomous agents with simple movement rules.